Valve Actuators for Bottom Ash High Pressure Spray Removal

Coal burning power plant

The pulverized coal boiler is the most common type of coal-burning furnace in the electric utility industry. After the pulverized coal is burned in a dry, bottom boiler, approximately 80 % of the unburned material or ash gets captured and recovered as fly ash. The remaining 20% of ash is categorized as bottom ash, a dark gray, granular, porous ash that is collected in a water-filled hopper at the bottom of the furnace. When a sufficient amount of bottom ash is collected in the hopper, it is purged by high pressure water jets into sluiceways or other conveyances for further processing.

Kinetrol Rotary Vane Actuator

The high pressure water (approx. 400 PSI) is actually recycled ash water and is very abrasive. The valves and control systems used to move the bottom ash slurry are typically 3” to 12” double offset, high-performance butterfly valves. Double acting pneumatic actuators are most common for opening and closing. Cycle frequency varies, but most typically are between 3 to 12 times per day.

Its crucial that the double offset valves seat completely and are truly “zero-leakage”. In this high pressure and high abrasion scenario, even the slightest leak will cause a rapid failure of the valve seat.

Rack and pinion, scotch yoke, and electric actuators are problematic because of the inherent hysteresis in their gearing. This hysteresis compounds over time adding to the amount of error introduced and increasing the likelihood of a poorly closed valve.

Rotary vane actuators, on the other hand, provide “hysteresis-free” seating due to their single moving part and one piece vane and shaft design. When mounted to the butterfly valves with a no-play coupler, the valve disc is guaranteed to close tightly, without degradation over time.

Additional benefits of using the vane actuator is smooth, controlled closing to reduce the possibility of water hammer and the greater ability work in poor quality atmospheres, both of which are considerations for this application.

Cement Silos Need Valve Actuators with Power and Reliability

Kinetrol spring return actuator on cement silo valve.

A silo is a structure for storing bulk materials. The cement silo is an integral piece of equipment for any concrete production operation as it allows the product to be stored, purchased and distributed in bulk. Fitted beneath silos, various types of butterfly or other rotary valves are used to control the flow of cement into trucks or other transport devices.

One particular cement processing plant needed a replacement for their main silo off loading valves. These valves fill cement trucks the company used to deliver their product.

The plant's existing valves were poorly applied for this use and were causing major headaches. The valves were designed with thin steel plate, large gaps between the valve body and disc, and rubber seals that wore away, leading to cement leaking through the valve. The leaking cement would spill onto a feed trough where it would cake and require manual cleaning - an expensive and time consuming operation. If the valve didn’t leak, this expense and time would be saved.

A custom valve manufacturer was called in to use their engineering and fabrication expertise to develop a custom valve that would last. The result was a new rotary valve that uses a much hardier wear plate, and the rotor and body are carefully machined with only a 2/100ths of an inch gap between them. Additionally, the design provides a mechanism to catch any cement should any ever make it through the gap.

The new, custom designed valve needed an actuator that would be equally reliable. The selection of Kinetrol vane actuator with a spring return was the most obvious because its power and its reliability. With only one moving part and no complex linkage to wear out, it was the best choice for long life. The combination of valve and actuator is expected to last many thousands of operations with no maintenance.

Procedure for Calculating Distance of Actuator from Hot Valve

The purpose of this post is to assist in determining the proper distance of a Kinetrol actuator from a hot valve.

In many situation, valves are put inline with a hot process media flowing through the piping system. In these situations, careful consideration must be taken to avoid over temperature exposure of the Kinetrol actuator via conductive or radiant heat.

The following formulae will assist in giving you data to calculate the safe distance between hot valve and actuator.

For steel RHS mount kits, standard (80°C Max.) actuators In ambient 50°C air. 

If you need assistance, or have any concerns about properly distancing the actuator from your process, it's always best to consult with the experts at Kinetrol USA. They're just a phone call away. For more information visit www.kinetrolusa.com or call 972-447-9443.

Kinetrol EL Positioner Option: Special Characteristic for Butterfly Valve Linear Flow Control

EL Positioner

EL positioner option: Special characteristic to give butterfly valve control for linear valve flow vs. input signal.

Upon request Kinetrol can supply a positioner fitted with a circuit that will provide an output characteristic to suit a butterfly valve. By replacing the standard circuit (with 10 non-linear and one linear control response curves) by one containing a microprocessor programmed with 10 different non-linear curves and one linear, the valve can be controlled to give optimum flow control with a butterfly valve.

In general the pressure drop across a valve will change as the valve opens, and this changes the flow/valve position characteristic. The five solid line curves on the graph linearise the response for valve pressure drops which fall to a range of values as the valve is opened fully, see below.

The values below are the pressure drop with the valve full open expressed as a percentage of the pressure drop with the valve closed.

• Curve -1 for 100% (this should be used to linearize a butterfly valve which is operating with a constant pressure drop)
• Curve -2 for 30%
• Curve -3 for 10%
• Curve -4 for 3% 
• Curve -5 for 1%

Click on graph for larger view.

Example 

A butterfly valve controlling the flow of a fluid with a 10% constant pressure drop, gives 50% of its fully open flow at an angle of opening of roughly 40 degrees. We would thus recommend the user set the control response to curve -3, here 12mA (half signal) would open the valve to 40 degrees to allow 50% flow rate. The user can select one of the eleven pre-programmed curves by going into SETUP mode.

Kinetrol + Plug Valve = Optimum Sludge Valve Performance

Water treatment plant

Sewage sludge is the semi-solid material that is produced during sewage treatment of industrial or municipal wastewater. Sludge blowdown valves are used in water and wastewater treatment systems that separate solids prior to filtration. These valves are particularly susceptible to fouling and ultimately prone to failure.

Many valve manufacturers specify high-pressure/high-torque actuators to overcome the sludge. Many times they choose linear type valves and screw-type linear actuators because they provide the brute force needed to push through the sludge. An unwanted side-effect of using linear valves and actuators is that the same force used to push the disc through the sludge, also causes valve damage by pushing and grinding solids into the valve seats, disc and seals. Eventually, the valve becomes so damaged it no longer provides proper shut-off.

Kinetrol actuator

Pneumatic scotch yoke and rack and pinion actuators, with quarter-turn valves, can provide the torque required for opening and closing the valve, and the nature of some quarter-turn valve designs protect internal parts from damage. Plug valves are designed this way and when combined with double acting pneumatic actuators that operate on a controlled time frequency, are a very reliable design for this application. The cycle frequency depends on the amount of solids in the media, and cycle times of opening and closing every 20 minutes are common. This cycle rate however, is problematic for scotch yoke and rack and pinion actuators, causing them to fail prematurely. In some cases the actuators fail in only 3 - 4 months of use.

For sludge applications, Kinetrol rotary vane actuators mounted on quarter-turn plug valves are a great choice . The combination of the high cycle actuator design, with the design benefits of a plug valve, offer wastewater treatment operators a valve assembly that will provide years of trouble-free life.

Kinetrol Series 180 - 189 Actuator Spring Removal Replacement Instructions

Kinetrol Spring
Return Actuator

Spring removal/replacement instructions for 180/189 spring return actuators.

For more information, visit www.kinetrolusa.com or call 972-447-9443.

Kinetrol Series 180 - 189 Actuator Spring Removal Replacement Instructions from Kinetrol USA

Fit and Forget, Worry-free Pneumatic Valve Actuators

Here's a short, narrated introduction to the Kinetrol vane actuator and their use on industrial valves. Kinetrol's 60 years of applying "fit & forget, worry about something else" actuators has rightfully earned their reputation for being the most durable, long-lasting valve actuator on the market today - a statement backed by a 4 million cycle warranty and documented, real-world field installations where the actuator provided upwards of 30 million maintenance-free cycles.

For more information, visit http://www.kinetrolusa.com.